Electrical drive circuit



1.. E. M GRATH ETAL 3,339,120

ELECTRICAL DRIVE CIRCUIT Aug. 29, 1967 Filed Feb. 15, 1963 INVENTORS LEO E. McGRATH LOREN L TRIBBY W mam m'onvs United States Patent 3,339,120 ELECTRICAL DRIVE CIRCUIT Leo E. McGrath, Dayton, and Loren L. Tribby, West Carrollton, Ohio, assignors to The National Cash Register Company, Dayton, Ohio, a corporation of Maryland Filed Feb. 13, 1963, Ser. No. 253,271 9 Claims. (Cl. 317-1485) ABSTRACT OF THE DISCLOSURE A solenoid operating drive circuit including a boost circuit for producing an initial boost current for rapid energization of a solenoid and a hold circuit for producing a subsequent hold current of lower value for maintaining the solenoid in energized condition without high power dissipation. A bistable device controls the boost circuit and is reset by a feedback circuit to terminate the boost current once it has reached a predetermined level, while the hold circuit is prevented by diode action from being effective until the boost current has substantially terminated.

This invention relates generally to electrical drive circuits, and in particular to electrical pinch roll and brake drive circuits for use in record media handling apparatus.

In high-speed record media handling devices, such as, for example, perforated tape readers, a brake and some sort of drive means, such as a pinch roll cooperating with a driving capstan, are commonly operated by solenoids in order to achieve rapid starting and stopping of tape movement. For high-speed operation of these solenoids, a relatively high boost current is commonly employed for initial energization, with a lower hold current being utilized to maintain the solenoid in energized condition.

In prior art devices, the high boost current and the lower hold current have been drawn from the same power supply, with a reduction in current value being achieved by use of a resistive element which is introduced into the circuit subsequently to initial energization of the solenoid by means of opening of a parallel relay control switch, or by some other means, to provide the lower hold current which is desired, once the solenoid has been energized. One reason for utilization of a lower hold current is that continued use of the higher boost current to maintain the solenoid energized would be likely to damage the solenoid, even though it is not harmful to the solenoid for short periods during energization. Also, the use of a lower hold current allows more rapid deenergization of the solenoid, since there is less energy in the winding.

The use of such a current limiting device is satisfactory where high power dissipation from the drive circuit is permissible. However, in some types of drive circuits, design considerations require a relatively low level of dissipation, and in such circuits, the resistive type of current limiting device is therefore not suitable.

The present invention is designed to overcome the problem of high dissipation, and is directed to a drive circuit which includes two different means for supplying power to either of two operating solenoids, one of said means providing a relatively high boost current for initial energization of each of said solenoids, and the second of said means providing a lower hold current for maintaining the solenoid in energized condition, once it has been energized. In addition, means are provided for terminating the boost current once it has reached a predetermined level, additional means are provided for terminating energization of the energized solenoid at any time in response to a change in input signal, and further means are provided for preventing operation of the hold current circuit means until the boost current has been terminated.

Accordingly, an object of the present invention is to provide an electrical drive circuit for accomplishing the foregoing objectives.

Another object is to provide a drive circuit capable of extremely rapid energization and deenergization of a solenoid.

A further object is to provide a drive circuit capable of producing an initial boost current for energization of a solenoid and a subsequent hold" current for maintaining said solenoid in energized condition.

An additional object is to provide a drive circuit capable of producing an initial boost current for energization of a solenoid, and capable of terminating said boost current when it reaches a given level.

Another object is to provide a drive circuit capable of producing an initial boost current for energization of a solenoid, capable of terminating said boost current when it reaches a given level, and capable of producing a hold current to maintain the solenoid in energized condition upon termination of the boost current.

Still a further object is to provide a drive circuit which includes first and second solenoid means, one of which may be used for control of a brake and the other of a tape driving means, said circuit also including boost current means for both of said solenoid means, hold" current means for each of said solenoid means, means for terminating the boost current applied to each of said solenoid means upon energization of said solenoids, means for preventing operation of the hold current means until operation of the boost current means has been terminated for each of the solenoid means, and input means for initiating operation of one of the boost current means for energizing one of said solenoid means, while preventing initiation of operation of the boost current means for energization of the other of said solenoid means.

Yet another object is to provide a drive circuit capable of producing an initial boost current for energization of a solenoid in response to an input signal, capable of terminating said boost current when it reaches a given level, capable of producing a hold current to maintain the solenoid in energized condition upon termination of the boost current, and capable of terminating energization of the solenoid at any time in response to a change in input signal.

Still a further object is to provide a solenoid drive circuit having high current boost means for energizing said solenoid, relatively low current hold means for maintaining the solenoid in energized condition, and having low power dissipation characteristics.

With these and other objects, which will become apparent from the following description, in view, the invention includes certain novel features of construction and combination of parts, a preferred form or embodiment of which is hereinafter described with reference to the accompanying drawing, in which the sole figure is a schematic circuit diagram of a drive circuit for producing boost and hold currents for energizing and maintain ing energized a brake means and a drive means, one of said means being deenergized when the other is energized.

Referring now to the drawing, five signal translating devices 10, 14, 18, 22, and 26 are utilized in a circuit for supplying an initial boost current to solenoid windings 30, which, in the illustrated embodiment, form part of a braking device (not shown) for halting movement of a continuous record medium, such as a perforated tape. The signal translating devices 10, 14, 18, 22, and 26 are illustrated as junction transistors of the p-n-p type. It is 3 to be understood that other types of signal translating devices may be utilized as the active elements of this portion of the circuit shown in the drawing, as well as in the remaining portions of said circuit, with appropriate changes of operating voltages to insure their proper operation. Examples of suitable components and component values for the cicruit shown in the drawing are given at the end of the specification.

The transistor includes an emitter electrode 11, a collector electrode 12, and a base electrode 13; the transistor 14 includes an emitter electrode 15, a collector electrode 16, and a base electrode 17; the transistor 18 includes an emitter electrode 19, a collector electrode 20, and a base electrode 21; the transistor 22 includes an emitter electrode 23, a collector electrode 24, and a base electrode 25; and the transistor 26 includes an emitter electrode 27, a collector electrode 28, and a base electrode 29.

The transistors 10 and 14 are cross-coupled in a conventional manner to form a bistable circuit, or flip-flop. The collector electrode 12 of the transistor 10 is connected over a parallel combination of a resistor 31 and a capacitor 32 to the base electrode 17 of the transistor 14, and the collector electrode 16 of the transistor 14 is connected over a parallel combination of a resistor 33 and a capacitor 34 to the base electrode 13 of the transistor 10. The emitter electrodes 11 and of the transistors 10 and 14 are connected to a base reference potential, shown here as ground; the collector electrodes 12 and 16 of the transistors 10 and 14 are connected over resistors 35 and 36, respectively, to terminals 37 and 38, respectively, to which are applied a source of negative energizing potential; and the base electrodes 13 and 17 of the transistors 10 and 14 are connected over resistors 39 and 40, respectively, to a terminal 41, to which is applied a source of positive energizing potential.

An input signal terminal 48 is also connected to the base electrode 17 of the transistor 14, a coupling capacitor 52, a point 51, and a unidirectional conducting device 50, which may be a semiconductor diode. The point 51 is connected over a resistor 53 to a base reference potential, shown as ground. The input signal appearing at the terminal 48 will be at one of two logical levels, designated for convenience as true and false. In the illustrated embodiment, the true level of the signal at the terminal 48 may be considered to be approximately zero volts, while the false signal has a value of approximately minus 8 volts. It will be understood, however, that other signal levels could easily be used by adjustment of the operating voltages and component values of the circuit.

A second input signal terminal 49 is also provided in the circuit, and the signal which appears thereon is, in all cases of normal circuit operation, the inverse of the signal appearing on the terminal 48. That is, if the signal on the terminal 48 is true, then the signal on the terminal 49 is false, and vice versa.

Any suitable means may be employed to impress the two signal levels on the input terminals 48 and 49. Such means may be a data-processing device or other mechanism from which it is desired to control the operation of the solenoids. Since such a device forms no part of the present invention, it is not shown or described herein.

The terminal 49 is connected to the base electrode 13 of the transistor 10, over a unidirectional conducting device 54, which may be a semiconductor diode, over a resistor 55, and over a point 56.

The collector electrode 16 of the transistor 14 is connected to the base electrode 21 of the transistor 18, over a resistor 57 and a point 58, which point is also connected over a resistor 59 to a terminal 60, to which is applied a source of positive energizing potential. The emitter electrode 19 of the transistor 18 is connected to a base reference potential, shown as ground, and the collector electrode of the transistor 18 is connected over a point 4 61 and a resistor 62. to a terminal 63, to which is applied a source of negative energizing potential.

The point 61 is also connected over a parallel combination of two unidirectional conducting devices 65 and 66, which may be semiconductor diodes, to a point 64, which point, in turn, is connected to a terminal 67 over a resistor 68. A source of positive energizing potential is applied to the terminal 67.

The point 64 is also connected to the base electrode 25 of the transistor 22. The emitter electrode 23 of the transistor 22 is connected over a point 69, a resistor 70, a point 71, and a unidirectional conducting device 72, which may be a semiconductor diode, to a terminal 73, to which is applied a source of positive energizing potential. The point 69 is also connected to the base electrode 29 of the transistor 26. The collector electrode 24 of the transistor 22 is connected over a point 74 to the collector electrode 28 of the transistor 26. The emitter electrode 27 of the transistor 26 is connected over a point 75 and a resistor 76 to a base reference potential, shown here as ground.

From the point 75, a circuit path extends over a voltage-regulating device 77, which may be a Zener-type diode, a point 78, a unidirectional conducting device 79, which may be a semiconductor diode, and a resistor 80, to the point 56, which, it will be recalled, is connected to the base electrode 13 of the transistor 10. The point 78 in the above-described circuit path is also connected over a resistor 81 to a terminal 82, to which is applied a source of positive energizing potential.

The point 74 in the collector electrode circuits of the transistors 22 and 26 is connected over a resistor 83, a point 84, a parallel combination of the solenoid windings 30 and a unidirectional conducting device 85, which may be a semiconductor diode, a point 86, and a point 87, to a terminal 88, to which is applied a source of negative energizing potential.

The circuit described above constitutes the boost driving circuitry for energizing the windings 30 of the brake-operating solenoid in the illustrated embodiment of the present invention.

A similar circuit, shown in the lower portion of the drawing, constitutes the boost driving circuitry for energizing the winding 101 of the pinch roll operating solenoid in the illustrated embodiment of the present invention. Included in this latter circuit are signal translating devices 102, 103, 104, 105, and 106, which may be p-n-p type junction transistors, as well as other associated components designated by appropriate reference numbers in the drawing. This latter circuit is nearly identical in the electrical configuration to the boost driving circuitry for energizing the windings 30 of the brake-operating solenoid, and differs slightly in component values, suitable examples of which are given at the end of the specification. Therefore no separate description will be given of the boost driving circuitry for energizing the winding 101 of the pinch roll operating solenoid. It may be noted that the input signals on the terminals 48 and 49, as applied to the boost circuitry for the winding 101, are the inverse of the signals applied to the boost circuitry for the windings 30, so that when the windings 30 are energized, the winding 101 is deenergized, and vice versa.

The hold circuitry associated with the two previously described boost circuits will now be described. Included in the hold circuitry are seven signal translating devices 156, 160, 164, 168, 172, 176, and 180, which are illustrated as junction transistors of the p-n-p type. As previously stated, it is to be understood that other types of signal translating devices may be utilized as the active elements of this portion of the circuit shown in the drawing, with appropriate changes of operating voltages to insure their proper operation.

The transistor 156 includes an emitter electrode 157, a collector electrode 158, and a base electrode 159; the transistor 160 includes an emitter electrode 161, a collector electrode 162, and a base electrode 163; the transistor 164 includes an emitter electrode 165, a collector electrode 166, and a base electrode 167; the transistor 168 includes an emitter electrode 169, a collector electrode 170, and a base electrode 171; the transistor 172 includes an emitter electrode 173, a collector electrode 174, and a base electrode 175; the transistor 176 includes an emitter electrode 177, a collector electrode 178, and a base electrode 179; and the transistor 180 includes an emitter electrode 181, a collector electrode 182, and a base electrode 183.

The base .electrode 159 of the transistor 156 is connected to the input terminal 48 over a point 190, a resistor 191, and a point 192. The point 192 is also connected over a resistor 193 to a terminal 194, to which is applied a positive source of energizing potential.

The emitter electrode 157 of the transistor 156 is connected to a base reference potential, shown here as ground, while the collector electrode 158 of said transistor is connected over a point 195 to the base electrode 163 of the transistor 160. From the point 195 a circuit path also extends over a resistor 196 and a point 197 to a terminal 198, to which is applied a negative source of energizing potential.

The emitter electrode 161 of the transistor 160 is connected over a point 201 to a terminal 202, to which is applied a negative source of energizing potential. The collector electrode 162 of the transistor 160 is connected over points 203 and 204, over a resistor 205, and over a point 206 to a terminal 200, to which is applied a nega tive source of energizing potential. The point 203 is also connected over a resistor 207 and a point 208 to the base electrode 171 of the transistor 168; and the point 204 is also connected over a resistor 209 and a point 210 to the base electrode 167 of the transistor 164.

The points 208 and 210 are connected together over a circuit path which includes a resistor 211, a point 212, and a resistor 213. The point 212 is connected over a point 214 to a terminal 215, which, in turn, is connected to a base reference potential, shown here as ground.

The emitter electrodes 165 and 169 of the transistors 164 and 168 are connected over the point 201 to the terminal 202, to which, it will be recalled, a negative source of energizing potential is applied. The collector electrode 166 of the transistor 164 is connected over a point 216 and a parallel combination of resistors 217 and 218 to the point 206, which, it will be recalled, is connected to the terminal 200, to which a negative source of energizing potential is applied. The collector electrode 170 of the transistor 168 is connected over a point 219, a resistor 220, and a point 221 to the base electrode 175 of the transistor 172. The point 219 is connected over a resistor 222 to a terminal 233, to which is applied a negative source of energizing potential, while the point 221 is connected over a resistor 224 to the point 214.

The emitter electrode 173 of the transistor 172 is connected to the terminal 202, to which, it will be recalled, a negative source of energizing potential is applied. The collector electrode 174 of the transistor 172 is connected over a point 225 and a parallel combination of resistors 226 and 227 to the point 197, and thence to the terminal 198, to which, it will be recalled, a negative source of energizing potential is applied.

The point 216 in the circuit of the collector electrode 166 of the transistor 164 is connected over a unidirectional conducting device 228, which may be a semiconductor diode, and over a point 229 to the base electrode 179 of the transistor 176. The point 229 is connected over a resistor 230 to a base reference potential, shown here as ground. The emitter electrode 177 of the transistor 176 is connected to a terminal 231, to which is applied a negative source of energizing potential.

The collector electrode 178 of the transistor 176 is connected over a resistor 232, a resistor 233, a unidirectional conducting device 234, which may be a semiconductor diode, and a point 235, to one side of the pinch roll solenoid winding 101. The other side of the winding 101 is connected to a point 236, and between the points 235 and 236, in parallel with the Winding 101, is a series combination of a unidirectional conducting device 143, which may be a semiconductor diode, and a resistor 144. The point 236 is connected to the point 87, which, it will be recalled, is connected to the terminal 88, to which is applied a negative source of energizing potential.

The point 225 in the collector electrode circuit 174 of the transistor 172 is connected over a unidirectional conducting device 237, which may be a semiconductor diode, and over a point 238, to the base electrode 183 of the transistor 180. The point 238 is connected over a resistor 239 to a base reference potential shown here as ground. The emitter electrode 181 of the transistor is connected to a terminal 240, to which is applied a source of negative energizing potential.

The collector electrode 182 of the transistor 180 is connected over a resistor 241, a resistor 242, and a unidirectional conducting device 243, which may be a semi-' conductor diode, to the point 84, which, it will be recalled, is connected to one side of the windings 30 for the brake solenoid. It will also be recalled that the other side of the windings 30 is connected over the points 86 and 87 to the terminal 88, to which is applied a negative source of energizing potential.

The operation of the electrical drive circuit of the present invention will now be described. Let it be assumed that the brake solenoid windings 30 are deenergized, so that the transistors 14 and 26 are non-conducting, the transistors 10 and 18 are conducting in a saturated condition, and the transistor 22 is operating in a class A condition. Let it also be assumed that a stop signal is gen erated,'so that the potential on the terminal 48 goes negatively to about minus 8 volts, while the potential on the terminal 49 goes positively to a level of about zero volt.

The negative-going signal at the terminal 48, coupled through the capacitor 52, causes the diode 50 to conduct, and said signal is applied to the base electrode 17 of the transistor 14, which causes said transistor to conduct. Since the transistors 10 and 14 are connected to form a fiip-flop, as previously described, the transistor 10 is thereby rendered non-conducting.

Conduction of the transistor 14 causes its collector electrode voltage to assume a level near ground, which causes the bias voltage developed across the resistors 36, 57, and 59, and applied to the base electrode of the transistor 18, to render said transistor non-conducting, so that its collector electrode voltage goes negative. This negative potential is coupled through the diode 65 and the conducting transistor 22 to the base electrode of the transistor 26, causing the transistor 26 to commence conducting. The collector electrode voltage of the transistor 18 is determined by the voltage across the resistor 76, the baseto-emitter voltage drops of the transistors 26 and 22, and the voltage drop across the diode 65.

When the transistor 26 is rendered conducting, the current through it commences anexponential rise toward a value of 30 amperes, its rise time being determined by the inductance of the brake solenoid windings 30, the series resistance of the resistors 76 and 83, and the resistance of the windings 30. It may be noted that during the boost period, the current rise through the windings 30 is almost linear. The increasing current through the transistor 26 causes the voltage at its emitter electrode to move in a negative direction, due to the voltage drop across the resistor 76.

Because of the relatively heavy current flowing through the windings 30, energization of the brake solenoid takes place in an extremely short period of time.

Due to the use of the Zener-type diode 77, the potential at the point 78 is maintained at a level eight volts more positive than the voltage at the emitter electrode of the transistor 26. Thus, as the emitter electrode voltage of the transistor 26 goes more negative, so does the voltage at the point 78, maintaining, however, a positive 8-volt differential, so that when the emitter electrode voltage becomes more negative than minus 8 volts, the potential at the point 78 becomes slightly negative with respect to ground. It may be noted that since the resistor 76 is a one-ohm resistor, one end of which is grounded, the emitter electrode potential becomes approximately minus 8 volts when a current of approximately 8 amperes is passing through the windings 30 of the brake solenoid.

When the potential at the point 78 becomes slightly negative with respect to ground, the diode 79 commences conducting, so that a negative potential is applied over the point 56 to the base electrode 13 of the transistor 10, causing said transistor to commence conducting.

Commencement of conduction in the transistor causes a positive-going signal from the collector electrode of said transistor to be applied to the base electrode of the transistor 14, thereby causing the transistor 14 to cease conducting. This, in turn, causes the collector electrode voltage of the transistor 14 to become more negative, and since such voltage is applied to the base electrode of the transistor 18, the transistor 18 is thereby rendered conducting once more.

The commencement of conduction in the transistor 18 causes its collector electrode voltage to become more positive, and this positive-going excursion of the collector electrode voltage is coupled through the conducting transistor 22 and applied to the base electrode of the transistor 26, thereby cutting off conduction in the transistor 26. The current path which extends from the terminal 88 through the windings 30, the transistor 26, and the resistor 76 to ground is thus interrupted.

Cutting off conduction through the transistor 26 causes its emitter electrode voltage to become a few tenths of a volt positive, which results in an approximately 8-volt positi've potential at the cathode of the Zener-type diode 77, which is also the potential at the point 78. As will be noted, this results in reverse biasing of the diode, 79, so that said diode acts as an open circuit. However, this does not affect the state of the transistor 10*, which remains in a conducting condition.

It will be seen that the feedback path through the diode 79, in coordination with the resistor 80, the resistor 81, the resistor 76, and the Zener-type diode 77, is essentially a current-sensing circuit which senses the output current of the transistor 26. This current-sensing circuit turns off the brake boost circuit described above when the required current magnitude through the windings 30 is reached.

In addition to turning off the brake boost circuit by means of the feedback path described above, said circuit may also be turned off at any time by application of a true signal to the terminal 48 and a false signal to the terminal 49. Such a signal is applied over the diode 54, the resistor 55, and the point 56 to the base electrode 13 of the transistor 10, to cause said transistor to commence conducting if it is not conducting at the time the signal is applied. Commencement of conduction of the transistor 10 is effective, as has been described above, to cut off conduction in the transistor 26 and thereby terminate the boost current through the windings 30 of the brake solenoid.

The mode of functioning of the boost circuit for applying an energizing current through the windings 101 of the pinch roll solenoid is essentially the same as has been described above in connection with the functioning of the boost circuit for the brake windings 30. Consequently, a separate detailed description will not be given of the functioning of the boost circuit for energization of the pinch roll solenoid winding 101.

The mode of operation of the hold circuits, for maintaining either the windings 30 of the brake solenoid or the winding 101 of the pinch roll solenoid in energized condition, once one of these has been energized, will now be described. As has been previously described, this hold circuit supplies a current to the brake or pinch roll solenoid windings, which is smaller than the boost current, but which is large enough to keep the selected solenoid in an energized condition.

In the initial condition of the circuit, as previously assumed, the transistors 156, 164, 168, and 180 are in a non-conducting condition, while the transistors 160, 172, and 176 are in a conducting condition.

When the previously assumed false level input signal appears on the terminal 48, this signal is applied over the point 190, the resistor 191, and the point 192 to the base electrode 159 of the transistor 156, thereby switching said transistor from a non-conducting condition to a conducting condition. The potential on the collector electrode 158 therefore approaches ground, and since this potential is applied to the base electrode 163 of the transistor over the point 195, the transistor 160 thereupon ceases conducting, and its collector electrode potential swings negatively toward minus 40 volts.

This negative-going excursion of potential is applied over the points 203 and 204 to the base electrodes 171 and 167 of the transistors 168 and 164, respectively, thereby renderingsaid transistors conducting. When these transistors are conducting, their collector electrode voltage is very near minus 28 volts.

The positive-going swing of the collector electrode voltage of the transistor 164 from near minus 40 volts to near minus 28 volts is applied to the base electrode 179 of the transistor 176 and cuts off conduction of said transistor. Similarly, the positive-going swing of the collector electrode voltage of the transistor 168 is applied over the point 219, the resistor 220, and the point 221 to the base electrode of the transistor 172, and causes said transistor to cease conducting.

With the transistor 176 out off, no energizing path is available for maintaining current through the winding 101 of the pinch roll solenoid, since the transistor 106 in the boost circuit for the winding 101 is also cut off at this time. Therefore the pinch roll solenoid is prevented from energizing. When conduction is cut off in the transistor 172, the collector electrode voltage swings negatively toward minus 40 volts, and this negative-going signal is applied over the point 225, the diode 237, and the point 238 to the base electrode 183 of the transistor 180, thereby conditioning said transistor for conduction.

However, due to the reverse bias of the diode 243, no conduction through the transistor 180 can take place until conduction of the transistor 26 in the brake boost circuit has terminated, because during the time that the transistor 26 is conducting, the potential at the cathode of the diode 243 is more positive than the potential at its anode, and conduction through said diode consequently cannot take place. Once the transistor 26 has been cut off, the potential at the point 84 becomes more negative, so that the diode 243 conducts, and conduction accordingly can take place through the transistor 180'. The current path which extends from the terminal 88 through the point 87, the windings 30, the point 84, the diode 243, the resistors 242 and 241, and the transistor 180 to the terminal 240 is sufiicient to maintain the windings 30 in energized condition. The above-described path is maintained until such time as the signal at the terminal 48 goes from a false level to a true level, and the signal at the terminal 49 goes from a true level to a false level, at which time the transistor 156- is cut off. This has the eifect, through the circuit previously described, of returning the transistors 164, 168, and 180 to a non-conducting condition, while the transistors 160, 172, and 176 are rendered conducting.

As has been stated, the present arrangement of the hold circuitry for the pinch roll solenoid and the brake solenoid assures that when the pinch roll solenoid is energized, the brake solenoid is deenergized, and vice versa. In this connection, it will be noted that the hold circuit for maintaining a current through the winding 101 of the pinch roll solenoid extends from the terminal 88 over the point 87, the point 236, the winding 101,

the point 235, the diode 234, the resistors 233 and 232,

and the transistor 176 to the terminal 231.

While it is understood that the circuit specifications of the electrical drive circuit of the present invention may vary according to the desired design for any particular application, the following circuit specifications for the circuit of the drawing are included by Way of example only:

Transistors 10, 14, 102, Type 2N404, manufac- 103, and 168 tured by Sylvania Electric Products,

Incorporated.

Type 2N396, manufactured by Ratheon Company.

Type 2N459, manufactured by Tung-Sol Electric, Incorporated.

Type 2N677, manufactured by Clevite Corporation.

Type 2Nl073, manufactured by Bendix Corportion.

Type 2N398, manufactured by Radio Corporation of America.

Type 2N597, manufactured by Philco Corporation.

Type 1N949, manufactured by Raytheon Transistors 18 and 104 Transistors 22 and 105 Transistor 26 Transistors 106, 176, and

Transistor 156 Transistors 160, 164, and

Semiconductor diodes 50,

132, and 141 Company. Semiconductor diodes 65, Type SD91, manufactured 7'2, and 13-3 by International Rectifie-r Corporation.

Type 6F 10, manufactured by International Rectifier Corporation.

Type SG22, manufactured by Tran-sitron Electronic Corporation.

Type SV128, breakdown voltage of -8 volts, manufactured by Transitron Electronic Corporation.

Winding of Type A- 39699-001 solenoid, manufactured by Ledex Inc.

Winding Type 1063 manufactured by United States Electronics Cor- Semiconductor diodes 85,

143, 234, and 243 Semiconductor diodes 228 and 2 37 Semiconductor Zener type diodes 77 and 138 Solenoid winding 30 Solenoid Winding 101 poration.

Ohms Resistor 31 3,900 Resistor 33 3,900 Resistor 35 10,000 Resistor 36 2,000 Resistor 39 36,000 Resistor 40 36,000 Resistor 53 15,000 Resistor 55 3,300 Resistor 57 1,000 Resistor 59 18,000 Resistor 62 250 Resistor 68 3,300 Resistor 70 500 Resistor 76 1 Resistor 80 100 Resistor 81 2,000

Ohms

Resistor 83 1 Resistor 108 3,300 Resistor 111 15,000 Resistor 112 10,000 Resistor 114 3,900 Resistor 116 a 3,900 Resistor 118 36,000 Resistor 119 36,000 Resistor 121 2,000 Resistor 123 18,000 Resistor 125 1,000 Resistor 128 680 Resistor 130 3,30 0 Resistor 134 910 Resistor 135 12 Resistor 136 12 Resistor 137 l2 Resistor 139 2,000 Resistor 142 100 Resistor 144 20 Resistor 191 4,300 Resistor 19'3 27,000 Resistor 196 a- 6,200 Resistor 205 470 Resistor 207 3,300 Resistor 209 820 Resistor 211 68,000 Resistor 213 68,000 Resistor 217 150 Resistor 218 150 Resistor 220 820 Resistor 222 910 Resistor 224 68,000 Resistor 226 150 Resistor 227 150 Resistor 230 910 Resistor 232 2 Resistor 233 2 Resistor 239 910 Resistor 241 2 Resistor 242 2 Micromicrofarads Capacitor 32 47 0 Capacitor 34 470 Capacitor 52 680 Capacitor 109 680 Capacitor 115 470 Capacitor 117 470 Terminal 37 Terminal 38 Terminal 41 Terminal 48 0 volt true signal and -8 volts false signal applied thereto. Terminal 49 0 volt true signal and 8 volts false signal applied thereto. Terminal 60 +20 volts applied thereto. Terminal 63 -28 volts applied thereto. Terminal 67 +20 volts applied thereto. Terminal 73 +20 volts applied thereto. Terminal 82 +20 volts applied thereto. Terminal 88 -40 volts applied thereto. Terminal 113 -28 volts applied thereto. Terminal 120 +20 volts applied thereto. Terminal 122 -28 volts applied thereto. Terminal 124 20 volts applied thereto. Terminal 129 -28 volts applied thereto. Terminal 131 +20 volts applied thereto. Terminal +20 volts applied thereto. Terminal 194 +20 volts applied thereto. Terminal 198 -40 volts applied thereto. Terminal 200 -40 volts applied thereto.

11 Terminal 202 28 volts applied thereto. Terminal 215 volt applied thereto. Terminal 223 --40 volts applied thereto. Terminal 231 -2-8 volts applied thereto. Terminal 240 28 volts applied thereto.

While the form of the circuit shown and described herein is admirably adapted to fulfill the objects primarily stated, it is to be understood that it is not intended to confine the invention to the one form or embodiment disclosed herein, for it is susceptible of embodiment in various other forms, within the scope of the appended claims.

What is claimed is:

1. An electrical drive circuit comprising, in combination,

solenoid means;

boost drive means for applying a relatively high energizing current to the solenoid means; a bistable device for :controlling the condition of said drive means;

input means to which signals having selectively a first level or a second level may be applied, which signals are capable of triggering the bistable device, to cause the boost drive means to energize the solenoid means in response to a signal change on the input means from said first level to said second level;

first control means for terminating operation of the boost drive means after the current applied by it to the solenoid means has reached a predetermined required value, by resetting the bistable device to its original condition, said control means including a voltage regulating device;

second control means associated with said input means for resetting said bistable device to its original condition in response to a signal change on the input means from said second level to said first level;

hold drive means for applying .a lower holding current to the solenoid means to maintain said means in energized condition after it has been energized; and

inhibiting means including a unidirectional conducting device for preventing operation of the hold drive means until operation of the boost drive means has substantially terminated.

2. An electrical drive circuit comprising, in combination,

solenoid means;

boost drive means for applying a relatively high energizing current to the solenoid means; a bistable device for controlling the condition of said drive means;

input means to which signals having selectively a first level or a second level may be applied, which signals are capable of triggering the bistable device to cause the boost drive means to energize the solenoid means in response to a signal change on the input means from said first level to said second level;

control means for terminating operation of the boost drive means after the current applied by it to' the solenoid means has reached a predetermined required value, by resetting the bistable device to its original condition, said control means including a Zener type diode for voltage regulation;

hold drive means conditioned for operation by a signal change on the input means, and operable to apply a lower holding current to the solenoid means to maintain said means in energized condition after it has been energized; and

inhibiting means including a unidirectional conducting device for preventing operation of the hold drive means until operation of the boost drive means has substantially terminated.

3. An electrical drive circuit comprising,

tion,

solenoid means;

boost drive means for applying a relatively high energizing current to the solenoid means; a bistable dein combinavice for controlling the condition of said drive means;

input means capable of triggering the bistable device to cause the boost drive means to energize the sole noid means; i

control means for terminating operation of the boost drive means after the current applied by it to the solenoid means has reached a predetermined required value, by resetting the bistable device to its original condition, said control means including a voltage regulating device;

hold drive means for applying a lower holding current to the solenoid means to maintain said means in energized condition after it has been energized; and

inhibiting means including a unidirectional conducting device for preventing operation of the hold drive means until operation of the boost drive means has substantially terminated.

4. An electrical drive circuit comprising, in combination,

solenoid means;

boost drive means for applying a relatively high energizing current to the solenoid means;

a bistable device for controlling the condition of said drive means, said bistable device when triggered atrom a first state to a second state controlling said drive means to energize said solenoid means;

input means to which signals having selectively a first level or a second level may be applied, which signals are capable of triggering said bistable device from said first state to said second state in response to a signal change on the input means from said first level to said second level;

first control means for resetting said bistable device from said second state to said first state when the current applied to said solenoid means reaches a predetermined value, to terminate said energizing current;

second control means associated with said input means for resetting said bistable device from said second state to said first state in response to a signal change on the input means from said second level to said first level; and

hold drive means for applying a lower holding current to the solenoid means to maintain it in energized condition after the operation of the boost drive means has been terminated by the first control means.

5. An electrical drive circuit comprising, in combination,

solenoid means;

boost drive means for applying a relatively high energizing current to the solenoid means;

a bistable device for controlling the condition of said drive means, said bistable device when triggered from a first state to a second state controlling said drive means to energize said solenoid means;

input means for triggering said bistable device from said first state to said second state;

control means for resetting said bistable device from said second state to said first state when the current applied to said solenoid means reaches a predetermined value, to terminate said energizing current, said control means including a Zener type diode and an additional unidirectional conducting device; and

hold drive means for applying a lower holding current to the solenoid means to maintain it in energized condition after the operatiton of the boos drive means has been terminated by the control means.

6. An electrical drive circuit comprising, in combination,

solenoid means;

boost drive means for applying a relatively high energizing current to the solenoid means;

a bistable device for controlling the condition of said drive means, said bistable device when triggered 13 from a first state to a second state controlling said drive means to energize said solenoid means;

input means for triggering said bistable device from said first state to said second state;

control means for resetting said bistable device from said second state to said first state when the current applied to said solenoid means reaches a predetermined value, to terminate said energizing current; and

hold drive means for applying a lower holding cur rent to the solenoid means to maintain it in energized condition after the operation of the boost drive means has been terminated by the control means.

7. An electrical drive circuit comprising, in combination,

solenoid means;

bistable means including two cross-coupled signal translating devices, said bistable means being capable of being triggered from a first state to a second state for producing an out-put for initiating energization of the solenoid means;

input means for triggering said bistable means from one state to another;

amplifying means including at least one signal translating device for amplifying the output from the bistable means and applying it to the solenoid means to energize said solenoid means;

control means including a voltage regulating device for resetting said bistable means from said second state to said first state when the energizing current applied by the amplifying means to the solenoid means reaches a predetermined value, to terminate said energizing current;

hold drive means for applying a holding current, of lower value than the energizing current, to the sole noid means to maintain it in energized condition after the bistable means has been reset to its first state; and

inhibiting means including a unidirectional conducting device for preventing operation of the hold drive means until the energizing current has been substantially terminated.

8. An electrical drive circuit comprising, in combination,

solenoid means;

bistable means including two cross-coupled transistors, said bistable means being capable of being triggered from a first state to a second state for producing an output for initiating energization of the solenoid means;

input means for triggering said bistable means from one state to another;

amplifying means including at least one transistor for amplifying the output from the bistable means and applying it to the solenoid means to energize said solenoid means;

control means including a voltage regulating device for resetting said bistable means from said second state to said first state when the energizing current applied by the amplifying means to the solenoid means reaches a predetermined value, to terminate said energizing current; and

hold drive means including at least one transistor for applying a holding current, of lower value than the energizing current, to the solenoid means to maintain it in energized condition after the bistable means has been reset to its first state.

9. An electrical drive circuit comprising, in combination,

solenoid means;

bistable means including two cross-coupled signal translating devices, said bistable means being capable of being triggered from a first state to a second state for producing an output for initiating energization of the solenoid means;

input means for triggering said bistable means from one state to another;

amplifying means including at least one signal translating device for amplifying the output from the bistable means and applying it to the solenoid means to energize said solenoid means;

control means including a voltage regulating device for resetting said bistable means from said second state to said first state when the energizing current applied by the amplifying means to the solenoid means reaches a predetermined value, to terminate said energizing current; and

hold drive means for applying a holding current, of

lower value than the energizing current, to the solenoid means to maintain it in energized condition after the bistable means has been reset to its first state.

References Cited UNITED STATES PATENTS FOREIGN PATENTS 6/1962 Great Britain.

MILTON O. HIRSHFIELD, Primary Examiner.

L. T. HIX, Examiner. 

1. AN ELECTRICAL DRIVE CIRCUIT COMPRISING, IN COMBINATION, SOLENOID MEANS; "BOOST" DRIVE MEANS FOR APPLYING A RELATIVELY HIGH ENERGIZING CURRENT TO THE SOLENOID MEANS; A BISTABLE DEVICE FOR CONTROLLING THE CONDITION OF SAID DRIVE MEANS; INPUT MEANS TO WHICH SIGNALS HAVING SELECTIVELY A FIRST LEVEL OR A SECOND LEVEL MAY BE APPLIED, WITH SIGNALS ARE CAPABLE OF TRIGGERING THE BISTABLE DEVICE, TO CAUSE THE "BOOST" DRIVE MEANS TO ENERGIZE THE SOLENOID MEANS IN RESPONSE TO A SAIGNAL CHANGE ON THE INPUT MEANS FROM SAID FIRST LEVEL TO SAID SECOND LEVEL; FIRST CONTROL MEANS FOR TERMINATING OPERATION OF THE "BOOST" DRIVE MEANS AFTER THE CURRENT APPLIED BY IT TO THE SOLENOID MEANS HAS REACHED A PREDETERMINED REQUIRED VALUE, BY RESETTING THE BISTABLE DEVICE TO ITS ORIGINAL CONDITIONS, SAID CONTROL MEANS INCLUDING A VOLTAGE REGULATING DEVICE; SECOND CONTROL MEANS ASSOCIATED WITH SAID INPUT MEANS FOR RESETTING SAID BISTABLE DEVICE TO ITS ORIGINAL CONDITION IN RESPONSE TO A SIGNAL CHANGE ON THE INPUT MEANS FROM SAID SECOND LEVEL TO SAID FIRST LEVEL; "HOLD" DRIVE MEANS FOR APPLYING A LOWER HOLDING CURRENT TO THE SOLENOID MEANS TO MAINTAIN SAID MEANS IN ENERGIZED CONDITION AFTER IT HAS BEEN ENERGIZED; AND INHIBITING MEANS INCLUDING A UNIDRIECTIONAL CONDUCTING DEVICE FOR PREVENTING OPERATION OF THE "HOLD" DRIVE MEANS UNTIL OPERATION OF THE "BOOST" DRIVE MEANS HAS SUBSTANTIALLY TERMINATED. 